Deoxidizing alloy and method



Patented Nov. 22 1938 UNITED. STATES PATENT OFFICE nEoxmizmG ALLOY AND METHOD Jerome Strauss, Pittsburgh, Pa., and George L.

Norris, Scarsdale, N. Y., assignors to Vana- Ilium Corporation of America, Bridgeville, Pa., a corporation of Delaware No Drawing. Application November 2, 1937, Serial No. 172,348

8 Claims. (c1. 75-5s) are the alloysfalling within the range of 'U. S.

Patent No. 1,853,229, such asone containing ap- 10 proximately 40 per cent iron, 40 per cent silicon, and 20 per cent aluminum, and one containing approximately 52 per cent iron, 18 per cent silicon, and 30 per cent aluminum.

The above 'mentioned iron-silicon-aluminum alloys are of low carboncontent, often containing much less than 0.15 per cent of'that element. They are heavy enough to sink beneath the surface of molten steel and iron, theirrate of reaction .with oxides in the molten bath is rapid enough to ensure deoxidatiori yet not so rapid as to permit loss of the effective elements or to react non-uniformly in the bath, they do not supply a significant amount of carbon to molten steel,

and during storage they do not disintegrate and 25 thus become finely powdered and therefore difficult to add to molten metal and to thus insure the inherent advantages just described of sinking readilyarid reacting with oxides not too rapidly, However, requirements of steel users in respect 10 to the cleanliness, or freedom from included oxides, silicates, and other reaction products, of

steels used for many purposes are becoming rapidly more restrictive. While the use of iron-siliconaluminum alloys such as those described above 15 offers in most cases the possibility of economically meeting present requirements of cleanliness and 5 low carbon iron product than has heretofore been commercially possible. In the prior art it Has been common practice to establish theoretically that to produce steels or or other compound was the most desirable one to form in molten baths of ferrous metals during their deoxidation; then calculate the composition of the addition alloy that would presumably produce this compound. The method has two lthe desirable combination of high strength, a 55 irons of superior cleanliness, a particular silicate serious disadvantages: first, the metals in an al- 103 do not react at rates determined by the percentages present but rather at rates resulting from this plus their inherent oxidizability as reflected in part in their heats of combination; second, other non-metallic substancesare dissolved by or react with the products of deoxidation and influence their properties such as melting temperature and viscosity. The alloys of the present invention have been discovered during the course 10. v

of experiments carried onin' a more practical manner-namely, by observing the actual effects produced in metals by addition of various alloys in comparison with the resultsobtained by the use of the above mentioned iron-silicon-aluminum 15 alloys and'others.

By these means it has been determined that the objective sought may be attained by alloys falling within the range of about 4 to 20 per cent titanium, 10 to 45 per cent silicon, 5 to 30 per cent 20 aluminum, and the remainder iron plus impurities.

There is a certain critical minimum for the titanium. The titanium must be at least about 4% and preferably in excess of 5%. Our studies of these alloys have shown that combinations prepared containing less than about 4% are ineffective in attaining the objective heretofore de- While the above broad ranges include all of the possible alloys with which it is possible to produce the desired effects, the preferred ranges most commonly employed are titanium 5 to 10%, aluthe above described limits are highly advantageous for the deoxidation and graphitization of cast irons and imthe manufacture of cast irons which -would be, under normal conditions of cooling,

either white or easily chilled in thin sections and at sharp corners. Such irons, which may possess highstrength due to the raw materials used or method of manufacture, or due to their chemical composition, will be caused to have finely distributed graphite particles of small size by the addition of' these titanium-aluminum-siliconiron alloys often added in such very small amounts as one ounce per one hundred pounds. ,In spite of very high strength they will be relatively free from any chilling tendency and thereby present proportionately high toughness and resistance to bending stresses, and easy machining. For this purpose, the titanium-aluminum-silicon iron alloys may contain as much as 2% carbon. The proportions of titanium, silicon and aluminum in the alloy are substantially the same as those employed when the alloy is to be added for deoxidizing steel, although the aluminum content is preferably not less than about 12% when the alloy is used as an addition to cast iron while the carbon may be increased above that present when the alloy is used as an addition to steel and low carbon irons.

In the deoxidation of some iron or steel baths the presence of large amounts of manganese is desirable and assists in obtaining the above noted objectives, namely, exceptional cleanliness in the case of steels, and control of deoxidation and graphitization in the case of cast irons. Moreover, the presence ofmanganese in large amounts in the alloy does not detract from any of the beneficial properties of compositions Within this range. The manganese may replace a small part of the iron, or it may replace the major part of the iron.

The following analyses of alloys made and used by us to produce deoxidized steels and irons of superior properties are typical:

0 Ti Al S1 Fe Mn 1. 75 ll. 25 i6. 32 25. 1O 42. 42 0. 85 D. 33 5. 65 8. 2O 37. 82 42. 68 0. 61 O. 04 8. 06 19. 31. 17 40. 77 0. 40 0. 97 5. 48 13. 92 2Q. 48 49. 0. 37 0. l2 16. 98 16. 86 11. 76 53. O0 1. 88 0. 06 12. 32 8. O0 13. 62 .42. 4O 23. 13 0.12 11. 3O 21. 01 26. 95 25. 04 15.

While we have described the preferred embodiment of our invention, the invention may be otherwise embodied and practiced within the scope of the following claims.

We claim:

1. The process of deoxidizing steels and irons which comprises adding to the molten metal an alloy containing titanium about 4 to 20 per cent,

aluminum about 8 to 30 per cent, silicon about 10 to 45 per cent, and carbon not over about 0.4 per cent, the balance being principally iron and manganese.

2. The process of deoxidizing and graphitizing cast iron which comprises adding to the molten metal an alloy containing titanium about 4 to 20 per cent, aluminum about 8 to 30 per cent, silicon about 10 to 45 per cent, and carbon not over about 2 per cent, the balance being principally iron and manganese.

3. An addition alloy for deoxidizing steel and iron containing titanium about 4 to 20 per cent, aluminum about 8 to 30 per cent, silicon about 10 to 45 per cent, and carbon not over about 0.4 per cent, the balance being principally iron.

4. An addition alloy for deoxidizing steel and iron containing titanium about 4 to 20 per cent,

aluminum about 8 to 30 per cent, silicon about 10 to 45 per cent, and carbon not over about 0.4 percent, the balance being principally iron and manganese.

5. An addition alloy for deoxidizing steel and iron containing titanium about 5 to 10 per cent, aluminum about 12 to 22 per cent, silicon about 28 to 38 per cent, and carbon not over about 0.4 per cent, the balance being principally iron.

6. An addition alloy for deoxidizing steel and iron containing titanium about 5 to 10 per cent, aluminum about 12 to 22 per cent, silicon about 28 to 38 per cent, and carbon not over about 0.4 per cent, the balance being principally iron and manganese.

7. An addition alloy for deoxidizing steel and iron containing titanium about 4 to 20 per cent, aluminum about 12 to 22 per cent, silicon about 10 to 45 per cent, and carbon not over about 2 per cent, the balance being principally iron.

8. An addition alloy for deoxidizing steel and iron containing titanium about 4 to 20 per cent, aluminum about 12 to 22 per cent, silicon about 10 to 45 per cent, and carbon not over about 2 per cent, the balance being principally iron and manganese.

JEROME STRAUSS. GEORGE L. NORRIS. 

